Observation door for pressurized furnaces



Nov. 12, 1963 J. P. CAREY 3,110,274

OBSERVATION DOOR FOR PRESSURIZED FURNACES Filed Dec. 29, 1960 2 Sheets-Sheet 1 INVENTOR.

Joseph P. Corey Nov. 12, 1963 J. P. CAREY OBSERVATION noon FOR PRESSURIZED FURNACES 2 Sheet-Sheet 2 Filed Dec. 29, 1960 MMMJJJAIL INVENTOR.

Joseph P. Corgy drmgm' 3,119,274 OBSERVATION DOGR FOR PRESSURIZED FURNACES Joseph 1. Carey, West Hartford, Conn, assigns: to Cornbustion Engineering, inc Windsor, Conn, a corporation of Delaware Fiied Dec. 29, 1960, Ser. No. 91,295 2 Claims. (Cl. 110-179) This invention relates to passageways or openings in walls of pressurized furnaces or other chambers under superatmospheric pressure, and particularly to such openings wherein fluid screen means are provided to prevent the escape of hot furnaces gases from such openings.

In many furnaces it is desirable to provide an opening for the purpose of observing the inside of the furnace, and to permit access to the furnace for the purpose of cleaning or lancing the furnace walls. In such furnaces some means must be provided for preventing the hot furnace gases from escaping through the opening when the door is open, which hot gases could cause considerable injury to personnel working in or around such opening.

It is an object of the present invention to provide an access opening with a suitable door, with means for directing or discharging a gaseous fluid under high pressure into the opening when the door is open, thus preventing the escape of hot gases from the furnace.

It is a further object of this invention to provide the door with a first safety means, whereby the valve controlling the flow of high pressure fluid to the directing or discharging means must be turned on before the door is capable of being opened.

It is another object to provide the door with a second safety means whereby the door can be partially or slightly opened, so that in case the high pressure gas is not being directed into the opening, the hot furnace gases will escape around the door through the small or slight opening, thereby warning the operator not to disengage the second safety means so as to fully open the door.

It is a still further object of this invention to provide the door with a window, whereby the inside of the furnace can be observed when the door is closed, and directing a low pressure fluid into the opening at such time to prevent dust, ash, or other foreign particles from accumulating on the window.

Other and further objects of the invention will become apparent to those skilled in the art as the description proceeds. An illustrative embodiment of this invention is shown in the accompanying drawing wherein:

FIGURE 1 is a front view of a furnace door;

FIGURE 2 is a top plan view of the furnace door looking along lines 2-2 of FIGURE 1; and

FIGURE 3 is a sectional side view of the furnace door looking along lines 33 of FIGURE 1.

Referring now to FIGURE 1, designates a door for closing an opening formed in the wall of a chamber under superatmospheric pressure, in this instance a pressurized furnace. Mounted in the door is a glass plate or window 12, through which the inside of the furnace can be observed when the door is closed. The glass plate 12 is secured to the door by means of annular ring 14, which ring is fixed to the door by means of a plurality of screws 16. This construction is also shown in FIGURE 3 of the drawings.

The door Ill has a flange or hinge portion 18, by means of which the door can be pivotally mounted on the furnace wall. The door is pivoted on rod 20, so that the door can be opened outwardly from the furnace wall, swinging about pivot rod 20, as seen in FIGURES 1 and 2.

The door is provided with a latch or locking means 22, which in the position shown in full lines in FIGURE 1,

prevents the door from being opened. By means of handle 24, the latch can be rotated approximately to the broken line position indicated in FIGURE 1, in which position the latch 22 will not restrict door movement, and thus will permit the door to be opened.

The latch and handle are pivoted on bolt 26, which bolt is secured to a three-way valve 28, best shown in FIG- URE 3. Handle 24 thus acts as the valve actuator for valve 28.

Valve 28, when resting in the position shown in full lines in FIGURE 1, connects pipe 34 to pipe 30, which leads to a suitable source of low pressure forced draft air flow. Pipe 34 leads into annular manifold 76, as seen in FIGURE 3. Fluids are allowed to flow from manifold 76 into the opening 74 by means of jets 72, which act as directing or discharging means for the fluid flowing from pipe 34. The low pressure fluid being discharged into opening 74 while the door 10 is closed prevents dust, ash, and other foreign particles from accumulating on the window, which would obstruct the view of the inside of the furnace.

When valve 28 is turned by the handle or valve actuator 24 to the position indicated by broken lines in FIG- URE l, pipe 34 is connected to pipe 32, which leads to a suitable force of high pressure air, such as a compressor. In this position of the valve actuator, it being clear of the door 10 thus permitting opening thereof, the high pressure gaseous fluid, preferably air, is directed into opening '74 and forms a fluid screen efiective to prevent fluid flow from the furnace out through the opening when the door is opened. In this manner, a first safety means is provided whereby the door 10 cannot be opened unless member 22 is moved clear of the door, which movement opens the valve 28, permitting high pressure fluid to be discharged into the opening 74-.

A second safety feature is also provided for the door. As shown in FIGURE 2, an eye bolt 44 is pivotally secured to housing 54 by means of rod 45. This bolt can be pivoted around so as to extend into a slot 52 contained in flange member 47 secured on the door 10, as shown in FIGURE 1. Wing nut 46 is threaded onto the end of eye bolt 44, and by tightening the wing nut, the door 10 can be tightly and securely closed. By unthreading nut 46 slightly, the door can be partially opened, or cracked open. In this position, if for some reason the high pressure fluid is not flowing into opening '74 to form an effective screen, hot furnace gases will escape around the door between it and the door frame, thereby warning the operator that something is amiss and the door should not be opened any further. Then the cause of the trouble, which could be a break in pipe 32 or 34, plugging up of jets 72, or a failure of the source of supply of the high ressure air, such as a compressor, could be located and fixed.

If when the door is partially opened no hot furnace gases are being emitted around the door to be detected by the operator, then the wing nut 46 can be unthreaded more, until the bolt can be pivoted out of slot 52, to allow the door to be fully opened. Lugs or enlarged portions 48, illustrated in FIGURES 1 and 2, are formed on flange 47 adjacent to slot 52 to prevent the bolt 44 from accidentally slipping out of slot 52, which would allow the door to be blown open by the hot furnace gases and cause possible injury to the operator. The above-described structure provides a second safety feature, whereby if for some reason high pressure air is not being discharged into opening '74 after the valve 28 has been opened, the operator can safely detect this while the door is only slightly or partially opened.

A second eye bolt 38 is pivotally secured to the housing 54 on the side of the door opposite to bolt 44 by means of rod Ztl, which also acts as the pivot for door It}, as best seen in FIGURE 2. The door is provided with a slot similar to slot 52 into which bolt 38 can be pivoted, and the bolt can be tightened by means of wing nut 42. The purpose of this second eye bolt and wing nut is to allow the door 19 to be tightly closed on the opening by applying equal pressure on the two sidm of the door, thereby effecting a perfect and even seal entirely around the edge of the door. In order to accomplish this, loose play must be allowed in the hinge of the door 1%. As shown in FIGURES 1 and 2, bore 36 in hinge member 18 is made.

larger than the pivot rod 20, thereby allowing the door to be tightly closed by means of both bolts 38 and 44, and their corresponding wing nuts 42 and 45. A sealing gasket 58, made of a suitable asbestos material, is fixed to the housing 54 surrounding the furnace opening (shown in FEGURE 3), and assures a tight seal when the door is closed.

As shown in FIGURES 2 and 3, housing 54- is secured to the furnace wall 56 in any well knownrmanner, such as by welding. Opening 50 in the top of the unit is for the purpose of connecting pipe 34 thereto if desired, because of limited space beneath the door. If this were done, then the latch and valve mechanism would be located above the door also. As shown, opening is closed off when not needed or used.

The operation of the'device is as follows: In the position of the valve actuator 22 shown in full lines in FIG- URE 1, with the door closed, low pressure fluid is being supplied to opening 74 to permit observation of the inside of the furnace. It should also be mentioned that the low pressure fluid is cool, and thus prevents to some extent a high temperature differential between the inside and outside of the furnace door, which might cause stresses that could break the glass window 12. In order to permit opening of the door, the latch 22 must be rotated approximately 90 to the broken line position of FIGURE 1, which automatically supplies high pressure fluid to opening 74 to form a fluid screen effective to prevent hot gases from escaping from the furnace. By unthreading wing nut 4-6 slightly, the door 19 can be cracked open, at which time the operator can check to see if a fluid screen has been formed in opening 74. If it has, then the wing nut 46 can be unthreaded sufficiently to allow the nut to'pass over lugs 48 when the eye bolt 44 is pivoted out of slot 52. Bolt 44, along with bolt 38, allows the door to be tightly closed by applying equal pressure to opposite sides of the door, thus assuring an even and complete seal around the entire edge of the door.

While I have illustrated and described a preferred embodiment of my invention, it will be understood that minor changes in construction and arrangement of parts may be made without departing from the spirit and scope of the invention as claimed. It is therefore intended that all matter contained in the description or shown in the accompanying drawings be interpreted as illustrative and not in a limiting sense.

What I claim is:

l. In combination a wall defining a chamber containing a superatmospheric pressure having a chamber wall opening therethrough having an inner end and an outer end, a door at the outer end of said wall opening, a hinged connection between said wall and said door which allows the door to be swung outwardly away from said wall, said hinged connection comprising a bore contained in the door through which a pin extends, said pin being fixed to the wall, discharge means for discharging a fiuid into said opening, a source of high pressure fluid, a valve effective to prevent fiow from said high pressure source to the discharge means when in a first position, and connecting said high pressure source to the discharge means when in a second position, a valve actuator connected to said valve, whereby in a first position said valve actuator maintains the valve in its first position and is adjacent to said door thereby preventing the door from being swung open, and when moved to a second position said valve actuator moves said valve to its second position and is away from said door, thereby permitting opening of said door, a first bolt pivotally secured to the wall of said chamber, a first slot in said door, into which first slot said first boltcan be pivoted, a first nut threaded onto said first bolt, a second bolt pivotally secured to the wall, a second slot in said door diametrically opposite said first slot, into which second slot said second bolt may be pivoted, a second nut threaded onto said second bolt, the first bolt being pivotally secured to the wall by the same pin on which the door is hinged, a lug secured to the door adjacent the second slot and extending upwardly out of the plane the door lies in, said iug being positioned such that when the second bolt is pivoted out of the second slot, the second nut passes over the ilug, whereby tightening of said first and second nuts while said first and second bolts are within said first and second slots, respectively, holds the door tightly closed, unthreading said first and second nuts slightly allows partial opening of the door, and unthreading said first and second nuts more permits said first and second bolts to be pivoted out of said first and second slots, thereby allowing said door to be fully opened, the bore contained in the door being an oversized bore with respect to the pin so there is loose play in the hinged connection, so that when said first'and second nuts are tightened to hold the door tightly closed, equal pressure is applied to opposite sides of the door, thus assuring an even andcomplete seal around the entire edge of the door.

2. The combination set 'forth in claim 1, including a source of 'low pressure fluid, a window in said door, and saidrvalve when in its first position connects said low pressure source to the discharge means.

References (Iited in the file of this patent UNITED STATES PATENTS 1,990,189 King Feb. 5, 1935 2,055,722 Hardgrove Sept. 29, 1936 2,105,309 Carleton Jan. 11, 1938 2,528,671 Selnick Nov. 7, 1950 2,758,554 Ohman Aug. 14, 1956 2,920,585 Grossman et a1. Jan. 12, 1960 FOREIGN PATENTS 589,737 Canada Dec. 29, 1959 1,209,394 France Sept. 21, 1959 

1. IN COMBINATION A WALL DEFINING A CHAMBER CONTAINING A SUPERATMOSPHERIC PRESSURE HAVING A CHAMBER WALL OPENING THERETHROUGH HAVING AN INNER END AND AN OUTER END, A DOOR AT THE OUTER END OF SAID WALL OPENING, A HINGED CONNECTION BETWEEN SAID WALL AND SAID DOOR WHICH ALLOWS THE DOOR TO BE SWUNG OUTWARDLY AWAY FROM SAID WALL, SAID HINGED CONNECTION COMPRISING A BORE CONTAINED IN THE DOOR THROUGH WHICH A PIN EXTENDS, SAID PIN BEING FIXED TO THE WALL, DISCHARGE MEANS FOR DISCHARGING A FLUID INTO SAID OPENING, A SOURCE OF HIGH PRESSURE FLUID, A VALVE EFFECTIVE TO PREVENT FLOW FROM SAID HIGH PRESSURE SOURCE TO THE DISCHARGE MEANS WHEN IN A FIRST POSITION, AND CONNECTING SAID HIGH PRESSURE SOURCE TO THE DISCHARGE MEANS WHEN IN A SECOND POSITION, A VALVE ACTUATOR CONNECTED TO SAID VALVE, WHEREBY IN A FIRST POSITION SAID VALVE ACTUATOR MAINTAINS THE VALVE IN ITS FIRST POSITION AND IS ADJACENT TO SAID DOOR THEREBY PREVENTING THE DOOR FROM BEING SWUNG OPEN, AND WHEN MOVED TO A SECOND POSITION SAID VALVE ACTUATOR MOVES SAID VALVE TO ITS SECOND POSITION AND IS AWAY FROM SAID DOOR, THEREBY PERMITTING OPENING OF SAID DOOR, A FIRST BOLT PIVOTALLY SECURED TO THE WALL OF SAID CHAMBER, A FIRST SLOT IN SAID DOOR, INTO WHICH FIRST SLOT SAID FIRST BOLT CAN BE PIVOTED, A FIRST NUT THREADED ONTO SAID FIRST BOLT, A SECOND BOLT PIVOTALLY SECURED TO THE WALL, A SECOND SLOT IN SAID DOOR DIAMETRICALLY OPPOSITE SAID FIRST SLOT, INTO WHICH SECOND SLOT SAID SECOND BOLT MAY BE PIVOTED, A SECOND NUT THREADED ONTO SAID SECOND BOLT, THE FIRST BOLT BEING PIVOTALLY SECURED TO THE WALL BY THE SAME PIN ON WHICH THE DOOR IS HINGED, A LUG SECURED TO THE DOOR ADJACENT THE SECOND SLOT AND EXTENDING UPWARDLY OUT OF THE PLANE THE DOOR LIES IN, SAID LUG BEING POSITIONED SUCH THAT WHEN THE SECOND BOLT IS PIVOTED OUT OF THE SECOND SLOT, THE SECOND NUT PASSES OVER THE LUG, WHEREBY TIGHTENING OF SAID FIRST AND SECOND NUTS WHILE SAID FIRST AND SECOND BOLTS ARE WITHIN SAID FIRST AND SECOND SLOTS, RESPECTIVELY, HOLDS THE DOOR TIGHTLY CLOSED, UNTHREADING SAID FIRST AND SECOND NUTS SLIGHTLY ALLOWS PARTIAL OPENING OF THE DOOR, AND UNTHREADING SAID FIRST AND SECOND NUTS MORE PERMITS SAID FIRST AND SECOND BOLTS TO BE PIVOTED OUT OF SAID FIRST AND SECOND SLOTS, THEREBY ALLOWING SAID DOOR TO BE FULLY OPENED, THE BORE CONTAINED IN THE DOOR BEING AN OVERSIZED BORE WITH RESPECT TO THE PIN SO THERE IS LOOSE PLAY IN THE HINGED CONNECTION, SO THAT WHEN SAID FIRST AND SECOND NUTS ARE TIGHTENED TO HOLD THE DOOR TIGHTLY CLOSED, EQUAL PRESSURE IS APPLIED TO OPPOSITE SIDES OF THE DOOR, THUS ASSURING AN EVEN AND COMPLETE SEAL AROUND THE ENTIRE EDGE OF THE DOOR. 